The problem is the amount of calcium in layer feed. There's more calcium in layer feed to help with the egg shell production in hens. It's hard to say if it's the layer or something else. If it's not eating, you can try mashing up some scrambled eggs or boiled egg yolk with the Starter & some water, see it that will entice it to eat.
Continue treating with the Corid (5 - 7 days), what dose are you using?
What other symptoms is the chick exhibiting?
Pic of it's poop?
Continue treating with the Corid (5 - 7 days), what dose are you using?
What other symptoms is the chick exhibiting?
Pic of it's poop?